// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/sync_socket.h"

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>

#if defined(OS_SOLARIS)
#include <sys/filio.h>
#endif

#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/threading/thread_restrictions.h"
#include "build/build_config.h"

namespace base {

namespace {
    // To avoid users sending negative message lengths to Send/Receive
    // we clamp message lengths, which are size_t, to no more than INT_MAX.
    const size_t kMaxMessageLength = static_cast<size_t>(INT_MAX);

    // Writes |length| of |buffer| into |handle|.  Returns the number of bytes
    // written or zero on error.  |length| must be greater than 0.
    size_t SendHelper(SyncSocket::Handle handle,
        const void* buffer,
        size_t length)
    {
        DCHECK_GT(length, 0u);
        DCHECK_LE(length, kMaxMessageLength);
        DCHECK_NE(handle, SyncSocket::kInvalidHandle);
        const char* charbuffer = static_cast<const char*>(buffer);
        return WriteFileDescriptor(handle, charbuffer, length)
            ? static_cast<size_t>(length)
            : 0;
    }

    bool CloseHandle(SyncSocket::Handle handle)
    {
        if (handle != SyncSocket::kInvalidHandle && close(handle) < 0) {
            DPLOG(ERROR) << "close";
            return false;
        }

        return true;
    }

} // namespace

const SyncSocket::Handle SyncSocket::kInvalidHandle = -1;

SyncSocket::SyncSocket()
    : handle_(kInvalidHandle)
{
}

SyncSocket::~SyncSocket()
{
    Close();
}

// static
bool SyncSocket::CreatePair(SyncSocket* socket_a, SyncSocket* socket_b)
{
    DCHECK_NE(socket_a, socket_b);
    DCHECK_EQ(socket_a->handle_, kInvalidHandle);
    DCHECK_EQ(socket_b->handle_, kInvalidHandle);

#if defined(OS_MACOSX)
    int nosigpipe = 1;
#endif // defined(OS_MACOSX)

    Handle handles[2] = { kInvalidHandle, kInvalidHandle };
    if (socketpair(AF_UNIX, SOCK_STREAM, 0, handles) != 0) {
        CloseHandle(handles[0]);
        CloseHandle(handles[1]);
        return false;
    }

#if defined(OS_MACOSX)
    // On OSX an attempt to read or write to a closed socket may generate a
    // SIGPIPE rather than returning -1.  setsockopt will shut this off.
    if (0 != setsockopt(handles[0], SOL_SOCKET, SO_NOSIGPIPE, &nosigpipe, sizeof nosigpipe) || 0 != setsockopt(handles[1], SOL_SOCKET, SO_NOSIGPIPE, &nosigpipe, sizeof nosigpipe)) {
        CloseHandle(handles[0]);
        CloseHandle(handles[1]);
        return false;
    }
#endif

    // Copy the handles out for successful return.
    socket_a->handle_ = handles[0];
    socket_b->handle_ = handles[1];

    return true;
}

// static
SyncSocket::Handle SyncSocket::UnwrapHandle(
    const TransitDescriptor& descriptor)
{
    return descriptor.fd;
}

bool SyncSocket::PrepareTransitDescriptor(ProcessHandle peer_process_handle,
    TransitDescriptor* descriptor)
{
    descriptor->fd = handle();
    descriptor->auto_close = false;
    return descriptor->fd != kInvalidHandle;
}

bool SyncSocket::Close()
{
    const bool retval = CloseHandle(handle_);
    handle_ = kInvalidHandle;
    return retval;
}

size_t SyncSocket::Send(const void* buffer, size_t length)
{
    ThreadRestrictions::AssertIOAllowed();
    return SendHelper(handle_, buffer, length);
}

size_t SyncSocket::Receive(void* buffer, size_t length)
{
    ThreadRestrictions::AssertIOAllowed();
    DCHECK_GT(length, 0u);
    DCHECK_LE(length, kMaxMessageLength);
    DCHECK_NE(handle_, kInvalidHandle);
    char* charbuffer = static_cast<char*>(buffer);
    if (ReadFromFD(handle_, charbuffer, length))
        return length;
    return 0;
}

size_t SyncSocket::ReceiveWithTimeout(void* buffer,
    size_t length,
    TimeDelta timeout)
{
    ThreadRestrictions::AssertIOAllowed();
    DCHECK_GT(length, 0u);
    DCHECK_LE(length, kMaxMessageLength);
    DCHECK_NE(handle_, kInvalidHandle);

    // TODO(dalecurtis): There's an undiagnosed issue on OSX where we're seeing
    // large numbers of open files which prevents select() from being used.  In
    // this case, the best we can do is Peek() to see if we can Receive() now or
    // return a timeout error (0) if not.  See http://crbug.com/314364.
    if (handle_ >= FD_SETSIZE)
        return Peek() < length ? 0 : Receive(buffer, length);

    // Only timeouts greater than zero and less than one second are allowed.
    DCHECK_GT(timeout.InMicroseconds(), 0);
    DCHECK_LT(timeout.InMicroseconds(),
        base::TimeDelta::FromSeconds(1).InMicroseconds());

    // Track the start time so we can reduce the timeout as data is read.
    TimeTicks start_time = TimeTicks::Now();
    const TimeTicks finish_time = start_time + timeout;

    fd_set read_fds;
    size_t bytes_read_total;
    for (bytes_read_total = 0;
         bytes_read_total < length && timeout.InMicroseconds() > 0;
         timeout = finish_time - base::TimeTicks::Now()) {
        FD_ZERO(&read_fds);
        FD_SET(handle_, &read_fds);

        // Wait for data to become available.
        struct timeval timeout_struct = { 0, static_cast<suseconds_t>(timeout.InMicroseconds()) };
        const int select_result = select(handle_ + 1, &read_fds, NULL, NULL, &timeout_struct);
        // Handle EINTR manually since we need to update the timeout value.
        if (select_result == -1 && errno == EINTR)
            continue;
        if (select_result <= 0)
            return bytes_read_total;

        // select() only tells us that data is ready for reading, not how much.  We
        // must Peek() for the amount ready for reading to avoid blocking.
        DCHECK(FD_ISSET(handle_, &read_fds));
        const size_t bytes_to_read = std::min(Peek(), length - bytes_read_total);

        // There may be zero bytes to read if the socket at the other end closed.
        if (!bytes_to_read)
            return bytes_read_total;

        const size_t bytes_received = Receive(static_cast<char*>(buffer) + bytes_read_total, bytes_to_read);
        bytes_read_total += bytes_received;
        if (bytes_received != bytes_to_read)
            return bytes_read_total;
    }

    return bytes_read_total;
}

size_t SyncSocket::Peek()
{
    DCHECK_NE(handle_, kInvalidHandle);
    int number_chars = 0;
    if (ioctl(handle_, FIONREAD, &number_chars) == -1) {
        // If there is an error in ioctl, signal that the channel would block.
        return 0;
    }
    DCHECK_GE(number_chars, 0);
    return number_chars;
}

CancelableSyncSocket::CancelableSyncSocket() { }
CancelableSyncSocket::CancelableSyncSocket(Handle handle)
    : SyncSocket(handle)
{
}

bool CancelableSyncSocket::Shutdown()
{
    DCHECK_NE(handle_, kInvalidHandle);
    return HANDLE_EINTR(shutdown(handle_, SHUT_RDWR)) >= 0;
}

size_t CancelableSyncSocket::Send(const void* buffer, size_t length)
{
    DCHECK_GT(length, 0u);
    DCHECK_LE(length, kMaxMessageLength);
    DCHECK_NE(handle_, kInvalidHandle);

    const int flags = fcntl(handle_, F_GETFL);
    if (flags != -1 && (flags & O_NONBLOCK) == 0) {
        // Set the socket to non-blocking mode for sending if its original mode
        // is blocking.
        fcntl(handle_, F_SETFL, flags | O_NONBLOCK);
    }

    const size_t len = SendHelper(handle_, buffer, length);

    if (flags != -1 && (flags & O_NONBLOCK) == 0) {
        // Restore the original flags.
        fcntl(handle_, F_SETFL, flags);
    }

    return len;
}

// static
bool CancelableSyncSocket::CreatePair(CancelableSyncSocket* socket_a,
    CancelableSyncSocket* socket_b)
{
    return SyncSocket::CreatePair(socket_a, socket_b);
}

} // namespace base
